Generally, a track serves to guide a train to a predetermined railroad as well as to distribute a load of the train, which is transmitted to a lower portion of the train, to protect a structure below the train. Also, driving stability and a ride comfort of the train are directly influenced by performance of the track, and most of a railroad environmental noise and vibration are caused by interaction between the track and a wheel. Thus, the track is a major factor directly affecting stability, economic feasibility, and comfortability of an entire railroad system.
However, such a track is undergone a very small amount of permanent deformation caused by passing of the train, and such deformation is accumulated as time passes to cause irregularity on a railroad surface. Specifically, since the track is configured with a simplified structure against an excessive train load acting while the train travels at a high speed, the track is a special structure that is required for a continuous maintenance in which renewal of a member is relatively frequently performed due to degradation of a material when compared to a general structure.
In repair of track irregularity, which already occupies a large part of a track maintenance work, a track inspection car has already been put into a practical use, and a state of the track has been regularly checked and the repair has been performed on the basis of a predetermined evaluation standard. In a sense, this is a repair system that is close to a monitored maintenance. However, in terms of priority of repair and an input amount thereof, data support is insufficient and thus, except that a mobilizable repair effort is first put into management of a special value, the remaining labor resources are sequentially distributed according to experience and intuition.
In the railroad, a role of the track is to surely realize a wheel runway defined by a track geometry, but in reality, there occurs an error. That is, the track serves to support and smoothly guide the train, but, when the track repetitively receives a load of the train, deformation gradually occurs on the track to cause unconformity with a running surface of a tracked vehicle, and this is called as track irregularity.
As a speed of the tracked vehicle increases, such track irregularity may cause a serious accident even with only small track irregularity.
For example, an increase in track irregularity may lead to an increased train jolt and deterioration in a ride comfort of a passenger, and, when such track irregularities become large or composite irregularities occur with other track irregularities, a derailment of a train may be caused. Therefore, a measurement of the track irregularity is a very important factor in ensuring stability of railroad transportation, and the need for measurement is gradually increasing even in terms of maintenance and repair of the railroad.
The track irregularity is an indicator of track maintenance, and is a decisive factor for driving stability of the train and a ride comfort of a passenger. The track maintenance is a task to restore the track irregularity within a predetermined standard limit, and it should be able to secure a ride comfort by ensuring prevention of accidents from the viewpoint of safety.
The track irregularity may be dynamically measured using a track inspection vehicle at regular intervals according to an operation of the train, or may be statically measured using a manpower or a simple inspection device as necessary.
Meanwhile, to secure driving stability and ride quality of a railroad vehicle, the track should be constructed and managed within a predetermined tolerance. Such a tolerance is called as track irregularity, and includes a height difference, direction misalignment, horizontal misalignment, warping, gauge, and the like. Among these inspection items, a method for inspecting the height difference and the direction misalignment is classified into two methods. The first method is a method for measuring a relative distance from a string that is spaced apart by a constant distance, that is, an inspection method using versine. This inspection method using versine is a method for mainly measuring displacement at three positions from a vehicle body to obtain an amount of a chord offset. Also, the second method is a method for measuring an absolute position in a space using a gyroscope and an accelerometer, and calculating track irregularity on the basis of the measured absolute position.
Meanwhile, FIG. 1 is a diagram illustrating a trolley-type track irregularity inspection device according to the related art, FIGS. 2A to 2C are photographs each illustrating in detail the trolley-type track irregularity inspection device shown in FIG. 1, FIG. 2A is a lateral view, FIG. 2B is a front view, and FIG. 2C illustrates sensors installed at a main measurement versine.
As shown in FIG. 1, the trolley-type track irregularity inspection device 10 according to the related art inspects track irregularity by installing a height sensor 11, a plane deformation sensor 12, a gauge sensor 13, and a level sensor 14, and, at this point, in the case of a height difference and direction misalignment, since the sensors are installed only on a left rail or a right rail, the height difference and the direction misalignment cannot be simultaneously measured on the left and right rails.
Accordingly, in the case of the trolley-type track irregularity inspection device 10 according to the related art, only one rail of the left and right rails is first measured, and then the other rail should be measured. In other words, the trolley-type track irregularity inspection device for measuring a height difference and direction misalignment of one rail has a problem in that the height difference and the direction misalignment should be measured on the left and right rails twice by moving a main measurement versine.
Meanwhile, as a prior art, Korean Registered Patent No. 10-737517 discloses the invention entitled “System and Method for Measuring Railroad Rail,” and it will be described with reference to FIGS. 3A and 3B.
FIGS. 3A and 3B are perspective views each illustrating a system for measuring a railroad rail according to the related art.
Referring to FIGS. 3A and 3B, the system for measuring a railroad rail according to the related art includes a main frame 61 which is a main measurement versine located in a direction perpendicular to a traveling direction of each of both left and right rails; a handle 62 provided at the main frame 61; an auxiliary frame 66 coupled to a right side of the main frame 61 in the same direction as the traveling direction of the right rail and relatively rotatably coupled to the main frame 61 by a hinge 63; a first horizontal roller 65a provided at both end portions of the auxiliary frame 66 and configured to rotate along an upper surface of the right rail; a first lateral roller 65b provided at both of the end portions of the auxiliary frame 66 and configured to rotate along an inner side surface of the right rail; a second horizontal roller 65d provided at a left distal end of the main frame 61 and configured to rotate along an upper surface of the left rail; a second lateral roller 65c provided at a left side of the main frame 61 and configured to be brought into close contact with and rotate along an inner side surface of the left rail; a gauge measurement sensor 21 provided at the left side of the main frame 61 and configured to emit a laser or an infrared ray toward the inner side surface of the left rail, receive the reflected light from the inner side surface thereof, and output a variation detection signal of gauge between the left and right rails; a height measurement sensor 22 provided at a central portion of the auxiliary frame 66 and configured to emit a laser or an infrared ray on the upper surface of the right rail, receive the reflected light from the upper surface thereof, and output a height detection signal of the right rail according to a time from the emitting and receiving of light; an angle measurement sensor 23 configured to measure whether an angle between the main frame 61 and the auxiliary frame 66 is 90° and output a detection signal; and a leveler 25 provided on an upper surface of the main frame 61 and configured to detect whether the main frame 61 is horizontal in a state in which the main frame 61 is hung on the left and right rails and output a detected level.
As shown in FIGS. 3A and 3B, the system for measuring a railroad rail according to the related art measures warping of a railroad rail, gauge irregularity thereof, flatness of an upper surface thereof, and horizontal misalignment thereof in consideration of gauge between left and right rails, a height therebetween, an ambient temperature, and the like so that maintenance and repair of the railroad rail may be easily performed and accidents and the like may be prevented in advance.
In such a system for measuring a railroad rail, the sensors detect the gauge and the height between the rails, a horizontal degree of each of the rails, and the ambient temperature, an analog-to-digital (A/D) converter converts analog signals from the sensors into corresponding digital signals, and a memory stores measured data. Also, an arithmetic part calculates an interval between the rails according to the output signals from the sensors on the basis of a contraction ratio and an expansion ratio of each of the rails according to a temperature, calculates a height difference between the rails, and calculate gauge between the rails and whether each of the rails is horizontal, and a display outputs the calculated results of the arithmetic part.
In other words, the system for measuring a railroad rail according to the related art may measure the height and the interval between the rails while moving along the railroad rail, and measure direction misalignment of the railroad rail, gauge irregularity, flatness of an upper surface of the rails, horizontal irregularity, and the like in consideration of the contraction ratio and the expansion ratio of each of the rails due to a difference in temperature, and thus it may employ a contact-type measurement method in which the system is in contact with the rails.
However, as described above, the system for measuring a railroad rail according to the related art should move the main measurement versine two times to measure the height difference and the direction misalignment of each of the left and right rails as shown in FIGS. 3A and 3B so that there is a problem in that a measurement time becomes long.
Also, to measure a versine height difference and versine direction misalignment, front and rear trolley wheels should be brought in close contact with the rails. Therefore, in a conventional system in which the front and rear trolley wheels are installed at a measurement frame and a single wheel is installed at another rail, the three wheels can be geometrically in close contact with the rails using a hydraulic pressure, a spring, or the like. However, when a left frame and a right frame are configured to have a rigid connected structure so as to simultaneously measure the left and right rails, left and right trolley wheels are not brought into close contact with the rails, so that there is a problem in that it is difficult to accurately measure the versine height difference and the versine direction misalignment.